1. Field of the Invention
The present invention relates to a method for manufacturing an epitaxial wafer formed of a silicon wafer and an epitaxial layer, the silicon wafer being loaded on a susceptor of an epitaxial growth apparatus to have the epitaxial layer formed on a main surface thereof while being rotated.
2. Description of the Related Art
In a method for manufacturing an epitaxial wafer, there is known that, when a silicon wafer is carried into a reactor having a high-temperature atmosphere by using a carrier blade of an epitaxial growth apparatus having an automatic carriage function, elastic deformation, i.e., so-called warpage is produced in the silicon wafer due to a thermal stress.
When the silicon wafer is loaded on a susceptor in a state where this warpage is produced, a back surface edge portion of the silicon wafer and the susceptor graze each other to generate particles and also produce extraneous materials at the time of remedying the warpage on the susceptor. Adherence of the extraneous materials to the silicon wafer is a serious problem in a manufacturing process.
To solve such a problem, there is disclosed a method for transferring a silicon wafer characterized in that a state where warpage of a heated and warped silicon wafer has been remedied is confirmed and then the silicon wafer is transferred onto a wafer support when transferring the silicon wafer to the wafer support from a carriage member through a transfer member (see, e.g., Japanese Patent Document 1).
Further, to solve the problem, as a technology that avoids warpage itself produced in a silicon wafer, there are disclosed a semiconductor manufacturing apparatus and a wafer handling method, the apparatus including controlling means for controlling heating by heating means to reduce a temperature difference between a front surface and a back surface of the silicon wafer and the apparatus executing an epitaxial growth process (see, e.g., Japanese Patent Document 2).
Patent Document 1
Japanese Examined Patent Application Publication No. Hei 10-294287 (claim 6)
Patent Document 2
Japanese Unexamined Patent Application Publication No. 2000-269137 (claim 3, claim 6)
However, in the invention disclosed in Patent Document 1, a remedy for warpage of the silicon wafer is carried out by a control unit. The control unit confirms a shape of a specific region of the silicon wafer when warped and a shape of the specific region of the same when not warped by comparing images from monitoring means, and transfers the silicon wafer from the silicon transfer member to the wafer support after confirming both the shapes. Therefore, the apparatus is complicated, a large cost is required to make alterations to the apparatus, and holding is required until the warped silicon wafer is restored into an original shape, thus involving a time loss in a manufacturing process.
Furthermore, in the invention disclosed in Patent Document 2, heating by the heating means is controlled in such a manner that a temperature difference between the front surface and the back surface of the silicon wafer is reduced to avoid warpage itself of the silicon wafer. Therefore, like Patent Document 1, the apparatus is complicated, and a large cost is required to make alterations to the apparatus. Moreover, since an effect is reduced and warpage of the silicon wafer becomes prominent as an outside diameter of the silicon wafer is increased, the above-explained problem cannot be solved in the silicon wafer having a large outside diameter.